Researchers from the MRC International Nutrition Group, based at the London School of Hygiene & Tropical Medicine and MRC Unit, The Gambia, utilized a unique ‘experiment of nature’ in rural Gambia, where the population’s dependence on own grown foods and a markedly seasonal climate impose a large difference in people’s dietary patterns between rainy and dry seasons.

Through a selection process involving over 2,000 women, the researchers enrolled pregnant women who conceived at the peak of the rainy season (84 women) and the peak of the dry season (83 women). By measuring the concentrations of nutrients in their blood, and later analysing blood and hair follicle samples from their 2-8 month old infants, they found that a mother’s diet before conception had a significant effect on the properties of her child’s DNA.

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The researchers found that infants from rainy season conceptions had consistently higher rates of methyl groups present in all six genes they studied, and that these were linked to various nutrient levels in the mother’s blood. Strong associations were found with two compounds in particular (homocysteine and cysteine), and the mothers’ body mass index (BMI) had an additional influence. However, although these epigenetic effects were observed, their functional consequences remain unknown.